Construction machines such as hydraulic shovels comprise a main body and a work equipment attached to the main body. The main body has a lower traveling body and an upper revolving body rotatably mounted on the lower traveling body via a revolving mechanism. The work equipment has a boom, an arm, a bucket, and other components, and the work equipment is attached to the upper revolving body. In such construction machines, the boom, the arm, and the bucket are driven by drive devices such as hydraulic cylinders, whereby various work can be performed.
In conventional practice, the boom, which is part of a work equipment such as the one described above, is formed by welding together a plurality of plate members (see Japanese Laid-Open Patent Application No. 2003-193512).